<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    }

    body {
      background: transparent;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-height: 100vh;
      padding: 16px;
    }

    .proof-grid {
      display: flex;
      flex-direction: column;
      align-items: center;
      width: 100%;
      max-width: 460px;
      gap: 12px;
    }

    .measurement-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      width: 100%;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 18px 12px;
      position: relative;
    }

    .number-display {
      display: inline-flex;
      align-items: center;
      font-variant-numeric: tabular-nums;
      gap: 4px;
    }

    .digit-group {
      display: inline-flex;
      align-items: center;
      position: relative;
      border-radius: 6px;
      padding: 2px 6px;
      transition: opacity 0.25s ease, background-color 0.25s ease;
    }

    .digit {
      font-size: 26px;
      font-weight: 700;
      line-height: 1.1;
      letter-spacing: -0.5px;
    }

    .decimal-point {
      font-size: 26px;
      font-weight: 700;
      line-height: 1.1;
      margin: 0 1px;
    }

    /* Leading Zeros Style - High contrast legible slate with indicator */
    .leading-zeros {
      background: #f1f5f9;
      border: 1.5px dashed #94a3b8;
      color: #475569;
    }

    .leading-zeros .digit,
    .leading-zeros .decimal-point {
      color: #475569;
    }

    /* Significant Digits Style */
    .sig-figs {
      background: #eff6ff;
      border: 1.5px solid #3b82f6;
      color: #1d4ed8;
    }

    .sig-figs .digit,
    .sig-figs .decimal-point {
      color: #1d4ed8;
    }

    .unit {
      font-size: 22px;
      font-weight: 700;
      color: #334155;
      margin-left: 2px;
    }

    /* Tag badges */
    .tag {
      position: absolute;
      font-size: 11px;
      font-weight: 700;
      letter-spacing: 0.3px;
      padding: 3px 8px;
      border-radius: 12px;
      white-space: nowrap;
    }

    .tag-placeholder {
      top: -10px;
      left: 12px;
      background: #fee2e2;
      color: #b91c1c;
      border: 1px solid #fca5a5;
    }

    .tag-sf {
      bottom: -10px;
      right: 12px;
      background: #dbeafe;
      color: #1d4ed8;
      border: 1px solid #93c5fd;
    }

    /* Connector */
    .connector {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 2px;
      color: #64748b;
    }

    .connector-line {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 12px;
      font-weight: 600;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #475569;
      padding: 4px 12px;
      border-radius: 16px;
      box-shadow: 0 1px 2px rgba(0, 0, 0, 0.04);
    }

    .arrow-icon {
      font-size: 13px;
      color: #2563eb;
      font-weight: 800;
    }

    /* Educational Takeaway Box */
    .takeaway-box {
      width: 100%;
      background: #eff6ff;
      border-left: 4px solid #2563eb;
      border-top: 1px solid #dbeafe;
      border-right: 1px solid #dbeafe;
      border-bottom: 1px solid #dbeafe;
      border-radius: 8px;
      padding: 10px 14px;
      display: flex;
      align-items: flex-start;
      gap: 8px;
    }

    .takeaway-icon {
      font-size: 16px;
      line-height: 1.3;
      flex-shrink: 0;
    }

    .takeaway-text {
      font-size: 12.5px;
      line-height: 1.45;
      color: #1e3a8a;
    }

    .takeaway-text strong {
      color: #172554;
      font-weight: 700;
    }

    /* Controls */
    .controls {
      display: flex;
      gap: 8px;
      margin-top: 2px;
    }

    .btn-toggle {
      background: #ffffff;
      border: 1px solid #cbd5e1;
      color: #1e2945;
      font-size: 12px;
      font-weight: 600;
      padding: 6px 14px;
      border-radius: 20px;
      cursor: pointer;
      display: flex;
      align-items: center;
      gap: 5px;
      transition: background 0.2s, border-color 0.2s, color 0.2s;
    }

    .btn-toggle:hover {
      background: #f8fafc;
      border-color: #94a3b8;
    }

    .btn-toggle.active {
      background: #1e2945;
      color: #ffffff;
      border-color: #1e2945;
    }

    /* Focus Mode effect */
    .focus-mode .leading-zeros {
      opacity: 0.25;
      filter: grayscale(80%);
    }

    @media (max-width: 380px) {
      .digit, .decimal-point, .unit {
        font-size: 22px;
      }
      .takeaway-text {
        font-size: 11.5px;
      }
      .tag {
        font-size: 10px;
        padding: 2px 6px;
      }
    }
  </style>
</head>
<body>

  <div class="proof-grid" id="proofGrid">
    
    
    <div class="measurement-row">
      <span class="tag tag-placeholder">✕ Placeholders only</span>
      
      <div class="number-display">
        <div class="digit-group leading-zeros" id="leadingGroup" title="Leading zeros serve only as decimal position markers">
          <span class="digit">0</span><span class="decimal-point">.</span><span class="digit">0</span><span class="digit">0</span>
        </div>

        <div class="digit-group sig-figs">
          <span class="digit">4</span><span class="digit">5</span>
        </div>

        <span class="unit">kg</span>
      </div>

      <span class="tag tag-sf">✓ 2 Sig Figs</span>
    </div>

    
    <div class="connector">
      <div class="connector-line">
        <span class="arrow-icon">⇅</span>
        <span>Equal quantity (1 kg = 1000 g)</span>
      </div>
    </div>

    
    <div class="measurement-row">
      <div class="number-display">
        <div class="digit-group sig-figs">
          <span class="digit">4</span><span class="decimal-point">.</span><span class="digit">5</span>
        </div>

        <span class="unit">g</span>
      </div>

      <span class="tag tag-sf">✓ 2 Sig Figs</span>
    </div>

    
    <div class="takeaway-box">
      <span class="takeaway-icon">💡</span>
      <div class="takeaway-text">
        Changing metric prefix eliminates leading zeros without changing the scale precision — both values have exactly <strong>2 significant figures</strong>.
      </div>
    </div>

    
    <div class="controls">
      <button class="btn-toggle active" id="btnBoth" onclick="setMode('both')">Side-by-Side</button>
      <button class="btn-toggle" id="btnFocus" onclick="setMode('focus')">Highlight Sig Figs</button>
    </div>

  </div>

  <script>
    function setMode(mode) {
      const grid = document.getElementById('proofGrid');
      const btnBoth = document.getElementById('btnBoth');
      const btnFocus = document.getElementById('btnFocus');

      if (mode === 'focus') {
        grid.classList.add('focus-mode');
        btnFocus.classList.add('active');
        btnBoth.classList.remove('active');
      } else {
        grid.classList.remove('focus-mode');
        btnBoth.classList.add('active');
        btnFocus.classList.remove('active');
      }
    }
  </script>
</body>
</html>

Identifying Significant Figures in Raw Measurements and Data

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      background: transparent;
      color: #1e293b;
      padding: 12px 8px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      min-height: 100%;
    }

    .comparison-container {
      display: flex;
      flex-direction: column;
      gap: 16px;
      width: 100%;
      max-width: 620px;
      margin: 0 auto;
    }

    .measurement-row {
      display: grid;
      grid-template-columns: auto 1fr auto;
      align-items: center;
      column-gap: 12px;
      row-gap: 6px;
    }

    /* Digit Pills */
    .digits-group {
      display: inline-flex;
      align-items: center;
      gap: 3px;
    }

    .digit-box {
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      min-width: 26px;
      height: 36px;
      border-radius: 6px;
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
      font-size: 17px;
      font-weight: 700;
      position: relative;
    }

    .sig-digit {
      background: #ecfdf5;
      border: 1.5px solid #10b981;
      color: #065f46;
    }

    .placeholder-digit {
      background: #f8fafc;
      border: 1.5px dashed #94a3b8;
      color: #64748b;
    }

    .decimal-marker {
      display: flex;
      align-items: flex-end;
      justify-content: center;
      padding-bottom: 4px;
      width: 10px;
      height: 36px;
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
      font-size: 24px;
      font-weight: 800;
      color: #0284c7;
      line-height: 1;
    }

    .unit {
      font-size: 14px;
      font-weight: 600;
      color: #64748b;
      margin-left: 4px;
    }

    /* Explanation & Rule */
    .rule-box {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 12.5px;
      color: #475569;
      line-height: 1.25;
    }

    .rule-arrow {
      color: #94a3b8;
      font-size: 14px;
      flex-shrink: 0;
    }

    .rule-text b {
      color: #0f172a;
    }

    .tag-placeholder {
      color: #dc2626;
      font-size: 11px;
      font-weight: 600;
      white-space: nowrap;
    }

    /* Sig Fig Count Badges */
    .sf-badge {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 6px 10px;
      border-radius: 9999px;
      font-size: 12.5px;
      font-weight: 700;
      white-space: nowrap;
      text-align: center;
    }

    .badge-slate {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #475569;
    }

    .badge-emerald {
      background: #d1fae5;
      border: 1px solid #6ee7b7;
      color: #065f46;
    }

    /* Responsive adjustments */
    @media (max-width: 480px) {
      .comparison-container {
        gap: 14px;
      }
      .measurement-row {
        grid-template-columns: 1fr auto;
      }
      .rule-box {
        grid-column: 1 / -1;
        padding-left: 2px;
        order: 3;
      }
      .digit-box {
        min-width: 23px;
        height: 32px;
        font-size: 15px;
      }
      .decimal-marker {
        width: 8px;
        height: 32px;
        font-size: 20px;
      }
      .sf-badge {
        padding: 4px 8px;
        font-size: 11.5px;
      }
      .rule-box {
        font-size: 11.5px;
      }
    }
  </style>
</head>
<body>

  <div class="comparison-container">
    
    <div class="measurement-row">
      <div class="digits-group">
        <div class="digit-box sig-digit">1</div>
        <div class="digit-box sig-digit">2</div>
        <div class="digit-box placeholder-digit">0</div>
        <div class="digit-box placeholder-digit">0</div>
        <span class="unit">m</span>
      </div>

      <div class="rule-box">
        <span class="rule-arrow">→</span>
        <span class="rule-text">No decimal <span class="tag-placeholder">(placeholders)</span></span>
      </div>

      <div class="sf-badge badge-slate">2 Sig Figs</div>
    </div>

    
    <div class="measurement-row">
      <div class="digits-group">
        <div class="digit-box sig-digit">1</div>
        <div class="digit-box sig-digit">2</div>
        <div class="digit-box sig-digit">0</div>
        <div class="digit-box sig-digit">0</div>
        <div class="decimal-marker">.</div>
        <span class="unit">m</span>
      </div>

      <div class="rule-box">
        <span class="rule-arrow">→</span>
        <span class="rule-text">Trailing decimal confirms measured</span>
      </div>

      <div class="sf-badge badge-emerald">4 Sig Figs</div>
    </div>

    
    <div class="measurement-row">
      <div class="digits-group">
        <div class="digit-box sig-digit">1</div>
        <div class="decimal-marker">.</div>
        <div class="digit-box sig-digit">2</div>
        <div class="digit-box sig-digit">0</div>
        <div class="digit-box sig-digit">0</div>
        <span class="unit">m</span>
      </div>

      <div class="rule-box">
        <span class="rule-arrow">→</span>
        <span class="rule-text">Decimal trailing zeros count</span>
      </div>

      <div class="sf-badge badge-emerald">4 Sig Figs</div>
    </div>
  </div>

</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <title>Significant Figures Breakdown</title>
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
      background: #ffffff;
      color: #1e293b;
      padding: 16px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      min-height: 100%;
    }

    /* Top Display */
    .display-row {
      display: flex;
      align-items: baseline;
      justify-content: center;
      gap: 3px;
      margin: 8px 0 16px 0;
    }

    .seg-btn {
      appearance: none;
      border: 2px solid transparent;
      background: #f8fafc;
      font-size: 32px;
      font-weight: 700;
      font-family: 'SF Mono', Monaco, Consolas, 'Liberation Mono', monospace;
      padding: 6px 10px;
      border-radius: 8px;
      cursor: pointer;
      display: flex;
      flex-direction: column;
      align-items: center;
      transition: all 0.25s ease;
      position: relative;
    }

    .unit {
      font-size: 26px;
      font-weight: 600;
      color: #94a3b8;
      padding-left: 6px;
      user-select: none;
    }

    /* Color States for Segments */
    .seg-lead { color: #64748b; background: #f1f5f9; border-color: #cbd5e1; }
    .seg-nz1  { color: #15803d; background: #dcfce7; border-color: #86efac; }
    .seg-cap  { color: #1d4ed8; background: #dbeafe; border-color: #93c5fd; }
    .seg-nz2  { color: #15803d; background: #dcfce7; border-color: #86efac; }
    .seg-trail{ color: #7e22ce; background: #f3e8ff; border-color: #d8b4fe; }

    .seg-btn.active {
      box-shadow: 0 0 0 3px #0ea5e9;
      transform: translateY(-2px);
    }

    .sig-index {
      font-size: 11px;
      font-weight: 700;
      margin-top: 2px;
      border-radius: 4px;
      padding: 1px 4px;
    }

    .lead-badge { background: #e2e8f0; color: #475569; }
    .sig-badge  { background: #bbf7d0; color: #14532d; }
    .cap-badge  { background: #bfdbfe; color: #1e3a8a; }
    .trail-badge{ background: #e9d5ff; color: #581c87; }

    /* Rules Card Deck */
    .card-container {
      width: 100%;
      max-width: 480px;
      position: relative;
      min-height: 120px;
    }

    .rule-card {
      position: absolute;
      inset: 0;
      border-radius: 10px;
      padding: 12px 16px;
      display: flex;
      flex-direction: column;
      justify-content: center;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.25s ease, transform 0.25s ease;
      transform: translateY(6px);
      border-width: 1.5px;
      border-style: solid;
    }

    .rule-card.active {
      opacity: 1;
      pointer-events: auto;
      transform: translateY(0);
    }

    .card-lead { background: #f8fafc; border-color: #cbd5e1; }
    .card-nz1  { background: #f0fdf4; border-color: #86efac; }
    .card-cap  { background: #eff6ff; border-color: #93c5fd; }
    .card-nz2  { background: #f0fdf4; border-color: #86efac; }
    .card-trail{ background: #faf5ff; border-color: #d8b4fe; }

    .rule-title {
      font-size: 15px;
      font-weight: 700;
      display: flex;
      align-items: center;
      justify-content: space-between;
      margin-bottom: 6px;
    }

    .rule-desc {
      font-size: 13.5px;
      color: #334155;
      line-height: 1.35;
    }

    .pill {
      font-size: 11px;
      font-weight: 700;
      padding: 3px 8px;
      border-radius: 12px;
      text-transform: uppercase;
      letter-spacing: 0.3px;
    }

    .pill-no { background: #fee2e2; color: #991b1b; }
    .pill-yes { background: #dcfce7; color: #166534; }

    /* Stepper Controls */
    .controls {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 12px;
      margin: 12px 0;
      width: 100%;
    }

    .btn-ctrl {
      background: #f1f5f9;
      border: 1px solid #cbd5e1;
      color: #334155;
      padding: 6px 14px;
      border-radius: 6px;
      font-size: 13px;
      font-weight: 600;
      cursor: pointer;
      display: inline-flex;
      align-items: center;
      gap: 4px;
      transition: background 0.2s;
    }

    .btn-ctrl:hover {
      background: #e2e8f0;
    }

    .dots {
      display: flex;
      gap: 6px;
    }

    .dot {
      width: 9px;
      height: 9px;
      border-radius: 50%;
      background: #cbd5e1;
      cursor: pointer;
      border: none;
      padding: 0;
      transition: background 0.2s, transform 0.2s;
    }

    .dot.active {
      background: #0ea5e9;
      transform: scale(1.25);
    }

    /* Summary Badge */
    .summary-badge {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      background: #0f172a;
      color: #ffffff;
      padding: 8px 18px;
      border-radius: 20px;
      font-size: 14px;
      font-weight: 700;
      letter-spacing: 0.2px;
      margin-top: 4px;
    }

    .summary-badge span {
      color: #38bdf8;
    }
  </style>
</head>
<body>

  
  <div class="display-row" id="segments">
    <button class="seg-btn seg-lead active" data-index="0">
      0.0
      <span class="sig-index lead-badge">0 SF</span>
    </button>
    <button class="seg-btn seg-nz1" data-index="1">
      5
      <span class="sig-index sig-badge">1st SF</span>
    </button>
    <button class="seg-btn seg-cap" data-index="2">
      0
      <span class="sig-index cap-badge">2nd SF</span>
    </button>
    <button class="seg-btn seg-nz2" data-index="3">
      4
      <span class="sig-index sig-badge">3rd SF</span>
    </button>
    <button class="seg-btn seg-trail" data-index="4">
      0
      <span class="sig-index trail-badge">4th SF</span>
    </button>
    <span class="unit">m</span>
  </div>

  
  <div class="card-container">
    
    <div class="rule-card card-lead active" id="card-0">
      <div class="rule-title" style="color: #475569;">
        <span>1. Leading Zeros</span>
        <span class="pill pill-no">NEVER COUNT</span>
      </div>
      <div class="rule-desc">
        Placeholders before the first non-zero digit.<br>
        <strong>0.0</strong> adds <strong>0 sig figs</strong>.
      </div>
    </div>

    
    <div class="rule-card card-nz1" id="card-1">
      <div class="rule-title" style="color: #15803d;">
        <span>2. Non-Zero Digit</span>
        <span class="pill pill-yes">ALWAYS COUNTS</span>
      </div>
      <div class="rule-desc">
        First measured non-zero digit.<br>
        <strong>5</strong> is the <strong>1st sig fig</strong>.
      </div>
    </div>

    
    <div class="rule-card card-cap" id="card-2">
      <div class="rule-title" style="color: #1d4ed8;">
        <span>3. Captive Zero</span>
        <span class="pill pill-yes">ALWAYS COUNTS</span>
      </div>
      <div class="rule-desc">
        Trapped between non-zero digits (5 and 4).<br>
        <strong>0</strong> is the <strong>2nd sig fig</strong>.
      </div>
    </div>

    
    <div class="rule-card card-nz2" id="card-3">
      <div class="rule-title" style="color: #15803d;">
        <span>4. Non-Zero Digit</span>
        <span class="pill pill-yes">ALWAYS COUNTS</span>
      </div>
      <div class="rule-desc">
        Standard measured non-zero digit.<br>
        <strong>4</strong> is the <strong>3rd sig fig</strong>.
      </div>
    </div>

    
    <div class="rule-card card-trail" id="card-4">
      <div class="rule-title" style="color: #7e22ce;">
        <span>5. Trailing Zero (with decimal)</span>
        <span class="pill pill-yes">COUNTS</span>
      </div>
      <div class="rule-desc">
        At the end of a number with a decimal point.<br>
        <strong>0</strong> is the <strong>4th sig fig</strong>.
      </div>
    </div>
  </div>

  
  <div class="controls">
    <button class="btn-ctrl" id="prevBtn">← Prev</button>
    <div class="dots" id="dotsGroup">
      <button class="dot active" data-index="0" aria-label="Step 1"></button>
      <button class="dot" data-index="1" aria-label="Step 2"></button>
      <button class="dot" data-index="2" aria-label="Step 3"></button>
      <button class="dot" data-index="3" aria-label="Step 4"></button>
      <button class="dot" data-index="4" aria-label="Step 5"></button>
    </div>
    <button class="btn-ctrl" id="nextBtn">Next →</button>
    <button class="btn-ctrl" id="playBtn" style="margin-left: 6px;">⏸ Auto</button>
  </div>

  
  <div class="summary-badge">
    ✓ Total = <span>4 Significant Figures</span>
  </div>

  <script>
    const segButtons = document.querySelectorAll('.seg-btn');
    const cards = document.querySelectorAll('.rule-card');
    const dots = document.querySelectorAll('.dot');
    const prevBtn = document.getElementById('prevBtn');
    const nextBtn = document.getElementById('nextBtn');
    const playBtn = document.getElementById('playBtn');

    let currentIndex = 0;
    let isPlaying = true;
    let timer = null;
    const totalSteps = 5;

    function showStep(index) {
      currentIndex = (index + totalSteps) % totalSteps;

      segButtons.forEach((btn, i) => {
        btn.classList.toggle('active', i === currentIndex);
      });

      cards.forEach((card, i) => {
        card.classList.toggle('active', i === currentIndex);
      });

      dots.forEach((dot, i) => {
        dot.classList.toggle('active', i === currentIndex);
      });
    }

    function startAutoPlay() {
      if (timer) clearInterval(timer);
      timer = setInterval(() => {
        showStep(currentIndex + 1);
      }, 3500);
      isPlaying = true;
      playBtn.textContent = '⏸ Auto';
    }

    function pauseAutoPlay() {
      if (timer) clearInterval(timer);
      isPlaying = false;
      playBtn.textContent = '▶ Play';
    }

    function toggleAutoPlay() {
      if (isPlaying) {
        pauseAutoPlay();
      } else {
        startAutoPlay();
      }
    }

    segButtons.forEach(btn => {
      btn.addEventListener('click', () => {
        pauseAutoPlay();
        showStep(parseInt(btn.getAttribute('data-index'), 10));
      });
    });

    dots.forEach(dot => {
      dot.addEventListener('click', () => {
        pauseAutoPlay();
        showStep(parseInt(dot.getAttribute('data-index'), 10));
      });
    });

    prevBtn.addEventListener('click', () => {
      pauseAutoPlay();
      showStep(currentIndex - 1);
    });

    nextBtn.addEventListener('click', () => {
      pauseAutoPlay();
      showStep(currentIndex + 1);
    });

    playBtn.addEventListener('click', toggleAutoPlay);

    // Initial launch
    startAutoPlay();
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      -webkit-tap-highlight-color: transparent;
      user-select: none;
    }

    body {
      width: 100%;
      height: 100%;
      background: #ffffff;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 12px;
      overflow: hidden;
    }

    /* Comparison Grid */
    .grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 12px;
      width: 100%;
      flex: 1;
      min-height: 0;
    }

    .measure-card {
      background: #ffffff;
      border: 1.5px solid #e6e6e6;
      border-radius: 12px;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: space-between;
      padding: 10px 8px;
      position: relative;
      cursor: pointer;
      transition: border-color 0.25s ease, box-shadow 0.25s ease;
    }

    .measure-card.active {
      border-color: #22b7ff;
      box-shadow: 0 0 0 3px rgba(34, 183, 255, 0.15);
    }

    .header-label {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      text-align: center;
      line-height: 1.2;
    }

    .sig-badge {
      display: inline-block;
      margin-top: 3px;
      font-size: 11px;
      font-weight: 600;
      padding: 2px 7px;
      border-radius: 10px;
      background: #f1f5f9;
      color: #475569;
    }

    .active .sig-badge {
      background: #e0f4ff;
      color: #0284c7;
    }

    /* SVG Apparatus Container */
    .visual-wrap {
      flex: 1;
      width: 100%;
      display: flex;
      align-items: center;
      justify-content: center;
      min-height: 0;
      padding: 4px 0;
    }

    svg {
      max-height: 100%;
      max-width: 100%;
    }

    /* Readout Footer */
    .readout {
      text-align: center;
      width: 100%;
    }

    .value-box {
      font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
      font-size: 16px;
      font-weight: 700;
      letter-spacing: -0.5px;
      padding: 4px 6px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 6px;
      display: inline-block;
    }

    .highlight-zeros {
      color: #0284c7;
      background: #e0f4ff;
      border-radius: 3px;
      padding: 0 2px;
    }

    .uncertainty {
      font-size: 11px;
      font-weight: 600;
      color: #64748b;
      margin-top: 3px;
    }

    /* Interactive Insight Banner */
    .banner {
      width: 100%;
      margin-top: 8px;
      padding: 6px 12px;
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 8px;
      font-size: 12px;
      color: #1e2945;
      display: flex;
      align-items: center;
      justify-content: space-between;
    }

    .banner-text {
      font-weight: 600;
    }

    .banner-highlight {
      color: #0284c7;
      font-weight: 700;
    }

    .tag-pill {
      font-size: 10px;
      font-weight: 700;
      text-transform: uppercase;
      padding: 2px 6px;
      background: #22b7ff;
      color: #fff;
      border-radius: 4px;
      letter-spacing: 0.5px;
    }
  </style>
</head>
<body>

  
  <div class="grid">
    
    
    <div class="measure-card active" id="cardBeaker" onclick="selectCard('beaker')">
      <div>
        <div class="header-label">Rough Volume</div>
        <div class="sig-badge">2 Sig Figs</div>
      </div>

      <div class="visual-wrap">
        <svg viewBox="0 0 120 140" width="110" height="130">
          
          <path d="M 25 15 L 20 20 L 25 20 L 25 125 A 10 10 0 0 0 35 135 L 85 135 A 10 10 0 0 0 95 125 L 95 20 L 100 20" 
                fill="none" stroke="#64748b" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round" />
          
          
          <path d="M 26 55 Q 60 58 94 55 L 94 125 A 9 9 0 0 1 85 134 L 35 134 A 9 9 0 0 1 26 125 Z" 
                fill="#38bdf8" fill-opacity="0.35" />
          
          
          <rect id="beakerZone" x="26" y="45" width="68" height="20" fill="#f59e0b" fill-opacity="0.2" rx="2" stroke="#f59e0b" stroke-width="1" stroke-dasharray="2 2" />
          
          
          <line x1="25" y1="115" x2="40" y2="115" stroke="#475569" stroke-width="1.5" />
          <text x="44" y="118" font-size="8" fill="#64748b" font-family="sans-serif">100</text>
          
          <line x1="25" y1="85" x2="40" y2="85" stroke="#475569" stroke-width="1.5" />
          <text x="44" y="88" font-size="8" fill="#64748b" font-family="sans-serif">200</text>
          
          
          <line x1="25" y1="55" x2="48" y2="55" stroke="#0284c7" stroke-width="2.5" />
          <text x="52" y="58" font-size="9" font-weight="bold" fill="#0284c7" font-family="sans-serif">250</text>
          
          <line x1="25" y1="28" x2="40" y2="28" stroke="#475569" stroke-width="1.5" />
          <text x="44" y="31" font-size="8" fill="#64748b" font-family="sans-serif">300</text>
        </svg>
      </div>

      <div class="readout">
        <div class="value-box">250 mL</div>
        <div class="uncertainty">Range: 240 – 260 mL</div>
      </div>
    </div>

    
    <div class="measure-card" id="cardSyringe" onclick="selectCard('syringe')">
      <div>
        <div class="header-label">Exact Volume</div>
        <div class="sig-badge">5 Sig Figs</div>
      </div>

      <div class="visual-wrap">
        <svg viewBox="0 0 120 140" width="110" height="130">
          
          <rect x="42" y="15" width="36" height="110" rx="3" fill="none" stroke="#64748b" stroke-width="2" />
          <line x1="30" y1="15" x2="90" y2="15" stroke="#64748b" stroke-width="3" stroke-linecap="round" />
          
          <path d="M 54 125 L 54 137 L 66 137 L 66 125 Z" fill="#94a3b8" />

          
          <rect x="44" y="50" width="32" height="75" fill="#38bdf8" fill-opacity="0.45" />

          
          <rect x="45" y="10" width="30" height="40" fill="#cbd5e1" fill-opacity="0.6" stroke="#64748b" stroke-width="1" />
          <line x1="43" y1="50" x2="77" y2="50" stroke="#0284c7" stroke-width="2.5" />

          
          <line x1="42" y1="35" x2="49" y2="35" stroke="#64748b" stroke-width="1" />
          <line x1="42" y1="40" x2="47" y2="40" stroke="#94a3b8" stroke-width="0.8" />
          <line x1="42" y1="45" x2="47" y2="45" stroke="#94a3b8" stroke-width="0.8" />
          <line x1="42" y1="50" x2="52" y2="50" stroke="#0284c7" stroke-width="1.5" />
          <line x1="42" y1="55" x2="47" y2="55" stroke="#94a3b8" stroke-width="0.8" />
          <line x1="42" y1="60" x2="47" y2="60" stroke="#94a3b8" stroke-width="0.8" />
          <line x1="42" y1="65" x2="49" y2="65" stroke="#64748b" stroke-width="1" />
          <line x1="42" y1="80" x2="49" y2="80" stroke="#64748b" stroke-width="1" />
          <line x1="42" y1="95" x2="49" y2="95" stroke="#64748b" stroke-width="1" />

          
          <rect x="22" y="70" width="76" height="26" rx="4" fill="#0f172a" stroke="#22b7ff" stroke-width="1.5" />
          <text x="60" y="87" font-size="11" font-weight="bold" fill="#22b7ff" font-family="ui-monospace, monospace" text-anchor="middle">250.00</text>
        </svg>
      </div>

      <div class="readout">
        <div class="value-box">250<span class="highlight-zeros">.00</span> mL</div>
        <div class="uncertainty">Range: 249.99 – 250.01 mL</div>
      </div>
    </div>

  </div>

  
  <div class="banner" id="infoBanner">
    <span class="banner-text" id="bannerDesc">Beaker uncertainty: <span class="banner-highlight">±10 mL</span></span>
    <span class="tag-pill" id="bannerPill">Estimated</span>
  </div>

  <script>
    function selectCard(type) {
      const beaker = document.getElementById('cardBeaker');
      const syringe = document.getElementById('cardSyringe');
      const desc = document.getElementById('bannerDesc');
      const pill = document.getElementById('bannerPill');

      if (type === 'beaker') {
        beaker.classList.add('active');
        syringe.classList.remove('active');
        desc.innerHTML = 'Beaker uncertainty: <span class="banner-highlight">±10 mL</span>';
        pill.textContent = 'Estimated';
        pill.style.background = '#64748b';
      } else {
        syringe.classList.add('active');
        beaker.classList.remove('active');
        desc.innerHTML = 'Extra zeros indicate <span class="banner-highlight">measured precision</span>';
        pill.textContent = 'Confirmed';
        pill.style.background = '#22b7ff';
      }
    }
  </script>
</body>
</html>

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta name="aspect-ratio" content="4:3">
  <style>
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
      font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    }

    body {
      background: #ffffff;
      color: #1e2945;
      display: flex;
      flex-direction: column;
      align-items: center;
      justify-content: center;
      padding: 16px;
      min-height: 100%;
    }

    .diagram-grid {
      display: flex;
      flex-direction: column;
      gap: 16px;
      width: 100%;
      max-width: 460px;
    }

    /* Example Card */
    .example-panel {
      background: #f8fafc;
      border: 1px solid #e2e8f0;
      border-radius: 12px;
      padding: 16px 14px;
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 10px;
    }

    .measurement-row {
      display: flex;
      align-items: center;
      justify-content: center;
      gap: 6px;
      position: relative;
    }

    .digit-box {
      width: 44px;
      height: 52px;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 26px;
      font-weight: 700;
      border-radius: 8px;
      transition: all 0.2s ease;
      user-select: none;
    }

    .dot-box {
      font-size: 28px;
      font-weight: 700;
      color: #64748b;
      margin: 0 -2px;
      align-self: flex-end;
      padding-bottom: 6px;
    }

    .unit-box {
      font-size: 20px;
      font-weight: 600;
      color: #64748b;
      margin-left: 4px;
    }

    /* Non-zero styling */
    .nonzero {
      background: #ecfdf5;
      border: 2px solid #10b981;
      color: #047857;
      box-shadow: 0 1px 3px rgba(16, 185, 129, 0.15);
    }

    /* Captive zero styling */
    .captive {
      background: #eff6ff;
      border: 2px solid #3b82f6;
      color: #1d4ed8;
      box-shadow: 0 0 10px rgba(59, 130, 246, 0.35);
      position: relative;
    }

    /* Trap brackets container */
    .bracket-wrap {
      display: flex;
      gap: 6px;
      position: relative;
    }

    .bracket-bar {
      position: absolute;
      top: -6px;
      left: 0;
      right: 0;
      height: 4px;
      background: #3b82f6;
      border-radius: 2px;
    }

    .bracket-bar::before,
    .bracket-bar::after {
      content: '';
      position: absolute;
      width: 2px;
      height: 6px;
      background: #3b82f6;
      bottom: -4px;
    }
    .bracket-bar::before { left: 0; }
    .bracket-bar::after { right: 0; }

    /* Summary pill */
    .badge-sigfig {
      font-size: 13px;
      font-weight: 700;
      color: #1e2945;
      background: #ffffff;
      border: 1px solid #cbd5e1;
      padding: 4px 12px;
      border-radius: 20px;
      display: flex;
      align-items: center;
      gap: 6px;
    }

    .badge-sigfig span {
      color: #2563eb;
    }

    /* Legend key */
    .legend {
      display: flex;
      justify-content: center;
      gap: 16px;
      width: 100%;
      max-width: 460px;
      padding-top: 4px;
      flex-wrap: wrap;
    }

    .legend-item {
      display: flex;
      align-items: center;
      gap: 6px;
      font-size: 12px;
      font-weight: 600;
      color: #475569;
    }

    .key-box {
      width: 14px;
      height: 14px;
      border-radius: 4px;
    }

    .key-green {
      background: #ecfdf5;
      border: 1.5px solid #10b981;
    }

    .key-blue {
      background: #eff6ff;
      border: 1.5px solid #3b82f6;
      box-shadow: 0 0 6px rgba(59, 130, 246, 0.4);
    }
  </style>
</head>
<body>

  <div class="diagram-grid">
    
    <div class="example-panel">
      <div class="measurement-row">
        <div class="digit-box nonzero" title="Non-zero digit">4</div>
        <div class="bracket-wrap">
          <div class="bracket-bar"></div>
          <div class="digit-box captive" title="Captive zero">0</div>
        </div>
        <div class="digit-box nonzero" title="Non-zero digit">8</div>
        <div class="unit-box">g</div>
      </div>
      <div class="badge-sigfig">
        Total: <span>3 Significant Figures</span>
      </div>
    </div>

    
    <div class="example-panel">
      <div class="measurement-row">
        <div class="digit-box nonzero" title="Non-zero digit">7</div>
        <div class="dot-box">.</div>
        <div class="bracket-wrap">
          <div class="bracket-bar"></div>
          <div class="digit-box captive" title="Captive zero">0</div>
          <div class="digit-box captive" title="Captive zero">0</div>
        </div>
        <div class="digit-box nonzero" title="Non-zero digit">2</div>
        <div class="unit-box">m</div>
      </div>
      <div class="badge-sigfig">
        Total: <span>4 Significant Figures</span>
      </div>
    </div>
  </div>

  
  <div class="legend">
    <div class="legend-item">
      <div class="key-box key-green"></div>
      <span>Non-zero (always counts)</span>
    </div>
    <div class="legend-item">
      <div class="key-box key-blue"></div>
      <span>Captive zero (trapped = counts)</span>
    </div>
  </div>

</body>
</html>

UK-GCSE-SCIENCE-WS-4-06

Aligned learning resources

Related diagrams